Samples that are deemed unacceptable for testing include those held for excessive storage times when thawed (in excess of 24 hours unfrozen or otherwise as determined by the Principal Investigator) or that are cracked or otherwise damaged. Samples having inadequate volume for initial and repeat testing in duplicate will not be tested as determined by the Charlotte NTL; a log will be kept of samples unacceptable for testing and the reason that the samples are unsuitable for testing.